1. Field of the Invention
The present invention relates to an air supply/exhaust device for an experimental animal rearing apparatus for rearing experimental animals, such as mice or rats and, more particularly, to an air supply/exhaust device capable of supplying fresh air into a box-shaped rearing cage or of exhausting air from the box-shaped rearing cage.
2. Description of the Related Art
Referring to FIGS. 5 to 7, a conventional experimental animal rearing apparatus (hereinafter referred to simply as rearing apparatus) comprises a rearing rack 2, a box-shaped rearing cages 3, air supply devices 4, automatic water supply devices 5 and, if necessary, air exhaust devices. As shown in FIG. 5, the rearing rack 2 is a vertical frame formed in the shape of a rectangular parallelepiped by assembling angle irons or the like, and having a back frame 6, a top frame and a bottom frame. The bottom frame is supported on four casters 7. Formed between the top and the bottom frame are, for example, three rearing cage storing spaces 8. Each rearing cage storing space 8 is capable of storing, for example, three box-shaped rearing cages 3 in a transverse arrangement.
As shown in FIG. 6, each box-shaped rearing cage 3 is made, for example, of a transparent plastic material and is provided with a flange 9 around an open upper end thereof. The open upper end of the box-shaped rearing cage 3 is covered with a lid 10. A rear end wall of the box-shaped rearing cage 3, i.e., an end wall to be in the back of the case storing space 8 when the box-shaped rearing cage 3 is stored in the case storing space 8, is provided with an opening 11 for receiving the air supply device 4, an opening 12 for receiving the automatic water supply device 5 and, if necessary, an opening, not shown, for receiving an air exhaust device.
As shown in FIGS. 6 and 7, the air supply device 4 has an air supply pipe 13 and a sealing cup 14. The air supply pipe 13 is provided in its upper part with, for example, four air supply holes 15 to blow air upward. The extremity of the air supply pipe 13 is closed with a pipe plug 16. The sealing cup 14 is fitted on the air supply pipe 13 so as to be set in contact with the outer surface of the rear end wall of the box-shaped rearing cage 3 when the rearing cage 3 is put in place in the case storing space 8. The air supply pipe 13 is attached to the back frame 6 so as to project into the case storing space 8 and is connected to an air blower, not shown. As shown in FIG. 7, the sealing cup 14 is formed in the shape of a cup having a diameter greater than that of the opening 11 of the box-shaped rearing cage 3 and provided with a flange 17 at its open end. The sealing cup 14 is fitted on the air supply pipe 13 so as to open toward the extremity of the air supply pipe 13.
Referring to FIG. 6, the automatic water supply device 5 has an outer pipe 18, a water supply pipe 19, and a sealing cup 20 similar to the sealing cup 14 of the air supply device 4. The outer pipe 18 is attached to the back frame 6 so as to project into the case storing space 8 and is connected to a main water supply pipe 21. The sealing cup 20 is fitted on the outer pipe 18 so as to open toward the extremity of the outer pipe 18. If necessary, an air exhaust pipe of the same construction as the air supply pipe 13 may be held on the back frame 6.
When the box-shaped rearing cage 3 is pushed into the case storing space 8, the air supply pipe 13 of the air supply device 4 and the outer pipe 18 of the automatic water supply device 5 are inserted through the openings 11 and 12, respectively, into the box-shaped rearing cage 3, and the respective flanges 17 and 22 of the sealing cups 14 and 20 are brought into close contact with the outer surface of the rear end wall of the box-shaped rearing cage 3. Consequently, the box-shaped rearing cage 3 is sealed and the air supply device 4 and the automatic water supply device 5 are joined firmly to the rear end wall of the rearing cage 3. Thus, fresh air and fresh water can always be supplied to animals, such as mice or rats, kept in the rearing cage 3. An air exhaust device can be joined to the rearing cage 3 in the same manner.
The sealing cup 14 of the air supply device 4 needs the flange 17 of a predetermined diameter to set the sealing cup 14 in close contact with the surface of the rear end wall of the rearing cage 3. The sealing cup 14 cannot be set in close contact with the outer surface of the rear end wall of the box-shaped rearing cage 3 unless the end surface of the flange 17 and the outer surface of the rear end wall of the rearing cage 3 are clean, smooth and flat. The same condition applies to the automatic water supply device 5. The sealing cups 14 and 20 have a large diameter and take a large space. The sealing cup 14 is unable to seal the interior of the rearing cage 3 properly and a gap may be formed between the end surface of the flange 17 and the outer surface of the rear end wall of the rearing cage 3 unless the sealing cup 14 is held on the air supply pipe 13 so that a plane including the end surface of the flange 17 is substantially perpendicular to the axis of the air supply pipe 13. The same condition applies to the sealing cup 20 of the automatic water supply device 5. Making the sealing cups 14 and 20 by molding rubber needs a mold having a spherical surface, which is not easy to make and increases the cost of the air supply device 4 and the automatic water supply device 5.